Hydrothermal synthesis of TiO2 nanopowders from tetraalkylammonium hydroxide peptized sols

Well-dispersed and highly crystallized anatase nano-crystals were synthesized by hydrothermally treating the titania sols after peptization with three types of tetraalkylammonium hydroxides (TANOHs), i.e. tetramethyl(ethyl, butyl)ammonium hydroxides (referred as TMNOH, TENOH, and TBNOH, respectively), which were observed by TEM and electron diffraction technique. All three peptizers enhance the growth of anatase particles. However, TMNOH-derived powders showed the largest particle size, whereas TBNOH-derived samples exhibited the smallest particle size. By increasing the peptizer concentrations, elongated structures were obtained in TMNOH-derived samples, while asterisk-structured particles appeared in TENOH-derived samples. No significant changes in particle shape were observed for the samples peptized with different amounts of TBNOH. These variations in particle size and shape arise from the alkalinity of TANOH, which greatly influence the growth of anatase particles.